1. Field of the Invention
The present invention relates to a process for forming an aluminum alloy thin film. Particularly the present invention relates to a process for forming an aluminum alloy thin film by utilizing a chemical vapor deposition technique (CVD method) applicable to wiring of semiconductor integrated circuits.
2. Description of the Related Art
In the field of semiconductor integrated circuits in which many circuit elements are integrated on a semiconductor substrate, demands for high integration have been increasingly made recently, and such demands require the wiring width on the integrated circuit to be refined.
Conventionally, aluminum (Al) has been used mainly for the wiring of semiconductor integrated circuits, but in accordance with the refining of the wiring width, problems such as electro-migration and stress-migration have occurred. In order to solve the problems, improvement in the quality of wiring metals has been sought. As a result, Al--Cu alloy, Al--Si alloy, Al--Si--Cu alloy etc. are now employed as wiring metals.
Meanwhile, an aluminum alloy thin film for wiring a semiconductor integrated circuit is conventionally formed by a spattering or bias-sputtering method. However, a ratio of the depth of a contact hole to the diameter of the hole has increased with a refining of the wiring width, in other words the aspect ratio (depth/diameter) has become higher. For this reason, it has become difficult to completely smooth contact holes by sputtering or a bias sputtering method. Further, there is also a fear that the wafer is damaged by impact of the electrons or ions existing in the spatter chamber.
The present invention has been achieved in order to solve the problems stated above, and it is an object of the present invention to provide a novel process for forming an aluminum alloy thin film.
It is another object of the present invention to provide a method for forming an aluminum alloy thin film, whereby a substrate is less impacted by ions etc.
It is still another object of the present invention to provide a method for forming an aluminum alloy thin film for the purpose of wiring sufficiently effective to deal with a refining of lining width entailed with the highly increased integration of semiconductor integrated circuits.